Generation of effector cells from T cell subsets III. Synergy between Lyt-1 and Lyt-123/23 lymphocytes in the generation of H-2-restricted and alloreactive cytotoxid T cells

1981 ◽  
Vol 11 (3) ◽  
pp. 246-250 ◽  
Author(s):  
Markus M. Simon ◽  
Andrew J. Edwards ◽  
Ulrich Hämmerling ◽  
Ian F. C. McKenzie ◽  
Klaus Eichmann ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
1979 ◽  
Vol 150 (6) ◽  
pp. 1293-1309 ◽  
Author(s):  
J E Swierkosz ◽  
P Marrack ◽  
J W Kappler

We have examined the expression of I-region antigens on functional subpopulations of murine T cells. A.TH anti-A.TL (anti-Ik, Sk, Gk) alloantiserum was raised by immunization of recipients with concanavalin A (Con A) stimulated thymic and peripheral T-cell blasts. In contrast to similar antisera made by conventional methods, the anti-Ia blast serum was highly cytotoxic for purified T lymphocytes. Moreover, it reacted in a specific fashion with T cells having particular functions. Treatment of keyhole limpet hemocyanin (KLH)-primed B10.A (H-2 alpha) T cells with this antiserum plus complement resulted in the elimination of helper activity for B-cell responses to trinitrophenyl-KLH. Inhibition was shown to be a result of the selective killing of one type of helper T cell whose activity could be replaced by a factor(s) found in the supernate of Con A-activated spleen cells. A second type of helper cell required for responses to protein-bound antigens appeared to be Ia-. By absorption and analysis on H-2 recombinants, at least two specificities were detectable on helper T cells; one mapping in the I-A subregion and a second in a region(s) to the right of I-J. In addition, the helper T cell(s) involved in the generation of alloreactive cytotoxic lymphocytes was shown to be Ia+, whereas cytotoxic effector cells and their precursors were Ia- with this antiserum. These results provide strong evidence for the selective expression of I-region determinants on T-cell subsets and suggest that T-cell-associated Ia antigens may play an important role in T-lymphocyte function.


Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 815-815
Author(s):  
Farhad Ravandi ◽  
Naval Daver ◽  
Guillermo Garcia-Manero ◽  
Christopher B Benton ◽  
Philip A Thompson ◽  
...  

Abstract Background: Blocking PD-1/PD-L1 pathways enhances anti-leukemia responses by enabling T-cells in murine models of AML (Zhang et al, Blood 2009). PD-1 positive CD8 T-cells are increased in bone marrow (BM) of pts with AML (Daver et al, AACR 2016). PD1 inhibition has shown activity in AML (Berger et al, Clin Cancer Res 2008). We hypothesized that addition of nivolumab to an induction regimen of ara-C and idarubicin may prolong relapse-free survival (RFS) and overall survival (OS); this study was designed to determine the feasibility of this combination. Methods: Pts with newly diagnosed acute myeloid leukemia (by WHO criteria; ≥20% blasts) and high risk MDS (≥10% blasts) were eligible to participate if they were 18-65 yrs of age and had adequate performance status (ECOG ≤3) and organ function (LVEF ≥ 50%; creatinine ≤ 1.5 g mg/dL, bilirubin ≤ 1.5 mg/dL and transaminases ≤ 2.5 times upper limit of normal). Treatment included 1 or 2 induction cycles of ara-C 1.5 g/m2 over 24 hours (days 1-4) and Idarubicin 12 mg/m2 (days 1-3). Nivolumab 3 mg/kg was started on day 24 ± 2 days and was continued every 2 weeks for up to a year. For pts achieving complete response (CR) or CR with incomplete count recovery (CRi) up to 5 consolidation cycles of attenuated dose ara-C and idarubicin was administered at approximately monthly intervals. Eligible pts received an allogeneic stem cell transplant (alloSCT) at any time during the consolidation or thereafter. Results: 3 pts with relapsed AML were treated at a run-in phase with a dose of nivolumab 1 mg/kg without specific drug-related toxicity. Subsequently, 32 pts (median age 53 yrs; range, 26-65) were treated as above including 30 with AML (24 de novo AML, 2 therapy-related AML, 3 secondary AML and 1 therapy-related secondary AML) and 2 high risk MDS. Pre-treatment genetic risk by ELN criteria was 11 adverse, 16 intermediate, and 5 favorable, including 2 FLT3 -ITD mutated, 5 NPM1 mutated, and 7 TP53 mutated. All 32 pts were evaluable for response and 23 (72%) achieved CR/CRi (19 CR, 4 CRi). The 4-week and 8 week mortality was 6% and 6%. The median number of doses of nivolumab received was 6 (range, 0-13); one pt did not receive nivolumab due to insurance issues. 9 pts underwent an alloSCT. After a median follow-up of 8.3 mths (range, 1.5-17.0) the median RFS among the responding pts has not been reached (range, 0.1 - 15.8 mths) and the median OS has not been reached (range 0.5-17.0 mths). Grade 3/4 immune mediated toxicities have been observed in 5 pts and include rash, pancreatitis, and colitis. Other grade 3/4 toxicities thought to be potentially related to nivolumab include cholecystitis in one pt. 9 pts proceeded to an alloSCT. Donor source was matched related in 2, matched unrelated in 6 and haplo-identical in 1 pt. Conditioning regimen was Fludarabine plus busulfan-based in 8, and fludarabine plus melphalan in 1 pt. 4 pts developed graft versus host disease (GVHD)(grade I/II in 3, grade III/IV in 1), which responded to treatment in 3. Multicolor flow-cytometry studies are conducted by the Immunotherapy Platform on baseline (prior to first dose of nivolumab) and on-treatment BM aspirate and peripheral blood to assess the T-cell repertoire and expression of co-stimulatory receptors and ligands on T-cell subsets and leukemic blasts, respectively. The baseline BM was evaluated on 23 of the 32 evaluable pts, including 18 responders and 5 non-responders. Pts who achieved a CR/CRi had a trend of higher frequency of live CD3+ total T cell infiltrate as compared to non-responders in the baseline BM aspirates (Fig 1A). We evaluated expression of immune markers on T cell subsets: CD4 T effector cells [Teff]: CD3+CD4+CD127lo/+Foxp3-, CD4 T regulatory cells [Treg]: CD3+CD4+CD127-Foxp3+, and CD8 T cells. At baseline, BM of non-responders had significantly higher percentage of CD4 T effector cells co-expressing the inhibitory markers PD1 and TIM3 (p<0.05) and a trend towards higher percentage of CD4 T effector cells co-expressing PD1 and LAG3 compared to responders (Fig 1B). Co-expression of TIM3 or LAG3 on PD1+ T cells have been shown to be associated with an exhausted immune phenotype in AML (Zhou et al., Blood 2011). Conclusion: Addition of nivolumab to ara-C and anthracycline induction chemotherapy is feasible and safe in younger pts with AML. Among the pts proceeding to alloSCT the risk of GVHD is not significantly increased. Figure 1 Figure 1. Disclosures Daver: Pfizer Inc.: Consultancy, Research Funding; Otsuka America Pharmaceutical, Inc.: Consultancy; Sunesis Pharmaceuticals, Inc.: Consultancy, Research Funding; Novartis Pharmaceuticals Corporation: Consultancy; Bristol-Myers Squibb Company: Consultancy, Research Funding; Kiromic: Research Funding; Karyopharm: Consultancy, Research Funding; Jazz: Consultancy; Immunogen: Research Funding; Daiichi-Sankyo: Research Funding; Incyte Corporation: Honoraria, Research Funding. Thompson: Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees. Jabbour: Bristol-Myers Squibb: Consultancy. Takahashi: Symbio Pharmaceuticals: Consultancy. DiNardo: Novartis: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Sharma: Jounce: Consultancy, Other: stock, Patents & Royalties: Patent licensed to Jounce; Astellas: Consultancy; EMD Serono: Consultancy; Amgen: Consultancy; Astra Zeneca: Consultancy; GSK: Consultancy; Consetellation: Other: stock; Evelo: Consultancy, Other: stock; Neon: Consultancy, Other: stock; Kite Pharma: Consultancy, Other: stock; BMS: Consultancy. Cortes: BMS: Consultancy, Research Funding; Sun Pharma: Research Funding; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding; ImmunoGen: Consultancy, Research Funding; ARIAD: Consultancy, Research Funding. Kantarjian: Delta-Fly Pharma: Research Funding; Amgen: Research Funding; ARIAD: Research Funding; Novartis: Research Funding; Bristol-Meyers Squibb: Research Funding; Pfizer: Research Funding.


2019 ◽  
Author(s):  
Jared Liu ◽  
Hsin-Wen Chang ◽  
Kristen M. Beck ◽  
Sahil Sekhon ◽  
Timothy H. Schmidt ◽  
...  

AbstractThe IL17A inhibitor secukinumab is efficacious for the treatment of psoriasis. In order to define its mechanism of action, it is important to understand its impact on psoriatic whole skin tissue as well as specific skin-resident immune cell populations such as T lymphocytes. In this study, we treated 15 moderate-to-severe plaque psoriasis patients with secukinumab and characterized the longitudinal transcriptomic changes of whole lesional skin tissue and cutaneous CD4+ T effector cells (Teffs), CD4+ T regulatory cells (Tregs), and CD8+ T effector cells during 12 weeks of treatment. Secukinumab was clinically effective, with 100%, 47%, and 27% of patients in the study achieving PASI75, PASI90, and PASI100 by week 12, respectively. At baseline prior to treatment, we observed that IL17A overexpression predominates in psoriatic CD8+ T cells rather than Teffs, supporting the importance of IL-17-secreting CD8+ T cells (Tc17) compared to IL-17-secreting CD4+ T cells (Th17) cells in the pathogenesis of psoriasis. Although secukinumab targets only IL17A, we observed rapid reduction of IL17A, IL17F, IL23A, IL23R, and IFNG expression in lesional skin as soon as 2 weeks after initiation of treatment and normalization of expression by week 12. Secukinumab treatment resulted in resolution of 89-97% of psoriasis-associated expression differences in both bulk tissue and T cell subsets by week 12 of treatment. Overall, secukinumab appears to rapidly reverse many of the molecular hallmarks of psoriasis.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2790-2790
Author(s):  
Theodora Anagnostou ◽  
Zhi-Zhang Yang ◽  
Hyojin Kim ◽  
Shahrzad Jalali ◽  
Jose C Villasboas ◽  
...  

The outcomes of lymphoma patients treated with PD1 inhibitors (PD1i) vary significantly across different histologies with objective responses rates that are around 70% in classical Hodgkin lymphoma, but significantly lower, around 10%, in indolent non-Hodgkin lymphomas (iNHL). This may be due in part to the inability of PD1i to restore the function of exhausted T-cells (Tex) in the tumor microenvironment (TME). PD1 is expressed on various T-cell subsets, including effector cells and Tex. In this study we sought to identify markers of exhaustion beyond PD1 that define T-cell subsets with high reactivation potential in marginal zone lymphoma (MZL). To define different stages of exhaustion in MZL, we developed and validated a mass cytometry (CyTOF) panel which integrates T-cell markers of lineage, differentiation, activation, suppression, cytokine production and transcription factors associated with exhaustion. We analyzed 35 MZL spleens obtained at diagnosis and 6 reactive spleens. We identified a population of CD8 cells in MZL that express TIM3 without PD1, compose 1.5% (range 0.14-4.88%) of total CD8 cells and expand with activation through the TCR (6.2% of CD8, range 0.6-14.2%). Prolonged cytokine exposure has been shown to induce exhaustion in healthy T-cells, and so to determine whether PD1-TIM3+ cells are Tex, we treated healthy donor T-cells with activating beads and IL12 and analyzed them by flow cytometry. We showed that PD1-TIM3+ cells expand with repetitive activation and IL12 treatment suggesting that they are Tex. Since Tex have been shown to have a distinct transcription profile compared to functional effector T-cells, we analyzed the expression of several transcription factors (TFs) that are upregulated in Tex by CyTOF and compared them to other subsets of T-cells. PD1-TIM3+ cells expressed higher levels of Eomes, Tbet, TOX and Helios compared to activated effector cells, confirming that they are Tex, but lower levels levels of the same TFs compared to PD1+TIM3+ cells, consistent with a less severely exhausted phenotype. To characterize the function of PD1-TIM3+ cells, we manually gated on subsets of CD8+ non-naïve cells that were stained with the CyTOF panel and compared the different subsets. We showed that PD1-TIM3+ cells arise from effector cells, maintain their polyfunctionality by producing cytokines and chemokines and have a unique cytokine production profile, including perforin, granzyme B and proinflammatory cytokines, such as IL17A. Importantly, PD1-TIM3+ cells produced higher levels of most cytokines compared to more severely Tex expressing both PD1 and TIM3 (Fig 1). We then performed tSNE analysis where similar objects are modeled by nearby points. We determined that PD1-TIM3+ cells cluster together, suggesting that they are phenotypically homogeneous cells in terms of function and expression of activation markers and are significantly different from PD1+TIM3+ cells (Fig 2). We finally blocked PD1 or TIM3 and analyzed the effect of each antibody blockade on function. We showed that TIM3 blockade was able to restore the production of most cytokines to higher degrees than PD1 blockade. In addition, TIM3 blockade led to upregulation of CD28, which is critical for the rescue of Tex through costimulation, while PD1 blockade did not. We then analyzed the clinical outcomes of all 34 MZL patients. The frequency of PD1-TIM3+ cells was lower among observed patients who failed to achieve an event-free survival (EFS) of 12 months (EFS12) (0.8% vs 1.7%, p=0.02) and among treated patients that failed an EFS of 24 months (EFS24) (0.9 vs 1.7%, p=0.03), when compared to patients that reached these endpoints. Higher levels of PD1-TIM3+ cells were also associated with a trend towards improved overall survival (OS). Five-year OS was 88% vs. 69% in patients with PD1-TIM3+ levels >2% and <2% of total CD8 cells respectively (p=0.1) (Fig 3). Our study provides insights into the mechanisms of failure of PD1i in MZL and identifies a novel population of Tex with high reactivation potential which is clinically relevant and could serve as a target for future immunotherapies in iNHL. Disclosures Anagnostou: American Society of Hematology, Mayo Clinic/Iowa Lymphoma SPORE, Mayo Clinic Immune Monitoring Core, Mayo Clinic Hematology Small Grant: Research Funding. Novak:Celgene Coorperation: Research Funding. Ansell:Mayo Clinic Rochester: Employment; Trillium: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; Seattle Genetics: Research Funding; Mayo Clinic Rochester: Employment; Affimed: Research Funding; LAM Therapeutics: Research Funding; Affimed: Research Funding; Seattle Genetics: Research Funding; LAM Therapeutics: Research Funding; Mayo Clinic Rochester: Employment; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; Trillium: Research Funding; Seattle Genetics: Research Funding; Bristol-Myers Squibb: Research Funding; Trillium: Research Funding; Mayo Clinic Rochester: Employment; Regeneron: Research Funding; Regeneron: Research Funding; Mayo Clinic Rochester: Employment; Seattle Genetics: Research Funding; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Affimed: Research Funding; Trillium: Research Funding; Mayo Clinic Rochester: Employment; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Trillium: Research Funding; Regeneron: Research Funding; Affimed: Research Funding; Seattle Genetics: Research Funding; Mayo Clinic Rochester: Employment; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Regeneron: Research Funding; Mayo Clinic Rochester: Employment; Regeneron: Research Funding; Trillium: Research Funding; Seattle Genetics: Research Funding; Seattle Genetics: Research Funding; Trillium: Research Funding; Regeneron: Research Funding; Affimed: Research Funding; LAM Therapeutics: Research Funding; Affimed: Research Funding; LAM Therapeutics: Research Funding; Regeneron: Research Funding; Affimed: Research Funding; Trillium: Research Funding; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Affimed: Research Funding; Affimed: Research Funding; Seattle Genetics: Research Funding; LAM Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; Trillium: Research Funding; LAM Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding.


Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2655
Author(s):  
Inesa Navasardyan ◽  
Benjamin Bonavida

The T cell-mediated immune response is primarily involved in the fight against infectious diseases and cancer and its underlying mechanisms are complex. The anti-tumor T cell response is regulated by various T cell subsets and other cells and tissues in the tumor microenvironment (TME). Various mechanisms are involved in the regulation of these various effector cells. One mechanism is the iNOS/.NO that has been reported to be intimately involved in the regulation and differentiation of the various cells that regulate the anti-tumor CD8 T cells. Both endogenous and exogenous .NO are implicated in this regulation. Importantly, the exposure of T cells to .NO had different effects on the immune response, depending on the .NO concentration and time of exposure. For instance, iNOS in T cells regulates activation-induced cell death and inhibits Treg induction. Effector CD8 T cells exposed to .NO result in the upregulation of death receptors and enhance their anti-tumor cytotoxic activity. .NO-Tregs suppress CD4 Th17 cells and their differentiation. Myeloid-derived suppressor cells (MDSCs) expressing iNOS inhibit T cell functions via .NO and inhibit anti-tumor CD8 T cells. Therefore, both .NO donors and .NO inhibitors are potential therapeutics tailored to specific target cells that regulate the T cell effector anti-tumor response.


2001 ◽  
Vol 69 (9) ◽  
pp. 5726-5735 ◽  
Author(s):  
Ulf Yrlid ◽  
Mattias Svensson ◽  
Anders Håkansson ◽  
Benedict J. Chambers ◽  
Hans-Gustaf Ljunggren ◽  
...  

ABSTRACT The present study was initiated to gain insight into the interaction between splenic dendritic cells (DC) and Salmonella enterica serovar Typhimurium in vivo. Splenic phagocytic cell populations associated with green fluorescent protein (GFP)-expressing bacteria and the bacterium-specific T-cell response were evaluated in mice given S. enterica serovar Typhimurium expressing GFP and ovalbumin. Flow cytometry analysis revealed that GFP-positive splenic DC (CD11c+ major histocompatibility complex class II-positive [MHC-II+] cells) were present following bacterial administration, and confocal microscopy showed that GFP-expressing bacteria were contained within CD11c+MHC-II+ splenocytes. Furthermore, splenic DC and T cells were activated following Salmonella infection. This was shown by increased surface expression of CD86 and CD40 on CD11c+ MHC-II+ cells and increased CD44 and CD69 expression on CD4+ and CD8+ T cells.Salmonella-specific gamma interferon (IFN-γ)-producing cells in both of these T-cell subsets, as well as cytolytic effector cells, were also generated in mice given live bacteria. The frequency of Salmonella-specific CD4+ T cells producing IFN-γ was greater than that of specific CD8+ T cells producing IFN-γ in the same infected animal. This supports the argument that the predominant source of IFN-γ production by cells of the specific immune response is CD4+ T cells. Finally, DC that phagocytosed live or heat-killed Salmonella in vitro primed bacterium-specific IFN-γ-producing CD4+ and CD8+ T cells as well as cytolytic effector cells following administration into naı̈ve mice. Together these data suggest that DC are involved in priming naı̈ve T cells toSalmonella in vivo.


Blood ◽  
2009 ◽  
Vol 113 (19) ◽  
pp. 4556-4565 ◽  
Author(s):  
Maria Nikolova ◽  
Jean-Daniel Lelievre ◽  
Matthieu Carriere ◽  
Armand Bensussan ◽  
Yves Lévy

Abstract The balanced manifestation of effector functions and the generation of long-living memory cells is a hallmark of efficient CD8+ T-cell response. Accumulating data pinpoint CD4+ CD25high regulatory T (Treg) cells as a key factor for the inefficiency of CD8+ T-cell responses in viral persistence. Little is known about the effects of Treg cells on the homeostasis of healthy donor CD8+ T cells. The present study demonstrates that Treg cells exert differential effects on CD8+ T-cell subsets. Treg cells inhibited mostly the polyclonal proliferation of CD27− effector cells compared with CD27+ memory CD8+ T cells. Moreover, they inhibited the polyclonal and antigen-driven differentiation of memory cells into functional effectors as defined by IFN-γ secretion and induction of CD160 expression. Finally, Treg cells reduced the apoptosis of memory but not of effector and terminal effector cell populations. These effects were at least in part mediated by a decreased expression of PD-L1, but not of programmed death 1 (PD-1), on CD8+ T cells after activation. Thus, in the setting of a healthy immune system, Treg cells fine-tune the memory/effector cell balance and promote the accumulation of long-living memory cells in case of strong stimulation.


2001 ◽  
Vol 194 (7) ◽  
pp. 953-966 ◽  
Author(s):  
Wolfgang Weninger ◽  
Maura A. Crowley ◽  
N. Manjunath ◽  
Ulrich H. von Andrian

It has been proposed that two different antigen-experienced T cell subsets may be distinguishable by their preferential ability to home to lymphoid organs (central memory cells) or nonlymphoid tissues (effector memory/effector cells). We have shown recently that murine antigen-primed CD8+ T cells cultured in interleukin (IL)-15 (CD8IL-15) resemble central memory cells in phenotype and function. In contrast, primed CD8+ T cells cultured in IL-2 (CD8IL-2) become cytotoxic effector cells. Here, the migratory behavior of these two subsets was investigated. Naive, CD8IL-15 cells and, to a lesser degree, CD8IL-2 cells localized to T cell areas in the spleen, but only naive and CD8IL-15 cells homed to lymph nodes (LNs) and Peyer's patches. Intravital microscopy of peripheral LNs revealed that CD8IL-15 cells, but not CD8IL-2 cells, rolled and arrested in high endothelial venules (HEVs). Migration of CD8IL-15 cells to LNs depended on L-selectin and required chemokines that bind CC chemokine receptor (CCR)7. Both antigen-experienced populations, but not naive T cells, responded to inflammatory chemokines and accumulated at sites of inflammation. However, CD8IL-2 cells were 12 times more efficient in migrating to inflamed peritoneum than CD8IL-15 cells. Furthermore, CD8IL-15 cells proliferated rapidly upon reencounter with antigen at sites of inflammation. Thus, central memory-like CD8IL-15 cells home avidly to lymphoid organs and moderately to sites of inflammation, where they mediate rapid recall responses, whereas CD8IL-2 effector T cells accumulate in inflamed tissues, but are excluded from most lymphoid organs.


Blood ◽  
2003 ◽  
Vol 102 (7) ◽  
pp. 2541-2546 ◽  
Author(s):  
Nuno L. Alves ◽  
Berend Hooibrink ◽  
Fernando A. Arosa ◽  
René A. W. van Lier

Abstract Recent studies in mice have shown that although interleukin 15 (IL-15) plays an important role in regulating homeostasis of memory CD8+ T cells, it has no apparent function in controlling homeostatic proliferation of naive T cells. We here assessed the influence of IL-15 on antigen-independent expansion and differentiation of human CD8+ T cells. Both naive and primed human T cells divided in response to IL-15. In this process, naive CD8+ T cells successively down-regulated CD45RA and CD28 but maintained CD27 expression. Concomitant with these phenotypic changes, naive cells acquired the ability to produce interferon γ (IFN-γ) and tumor necrosis factor α (TNF-α), expressed perforin and granzyme B, and acquired cytotoxic properties. Primed CD8+ T cells, from both noncytotoxic (CD45RA-CD27+) and cytotoxic (CD45RA+CD27-) subsets, responded to IL-15 and yielded ample numbers of cytokine-secreting and cytotoxic effector cells. In summary, all human CD8+ T-cell subsets had the ability to respond to IL-15, which suggests a generic influence of this cytokine on CD8+ T-cell homeostasis in man. (Blood. 2003;102:2541-2546)


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